well, I'd start by calling it something other than Warhammer of Fatality. Sounds quite plain.
what about "The Flatterer". Named by an Orc Chieftain with a faulty sense of vocabulary. Some mistake this weapon's abilities due to the peculiar name.
If you want a bit of silliness, how about if the Warhammer strikes its targets flat. Literally. Anyone hit becomes two-dimensional.
Anoher idea is, yes, the Warhammer crushes well, and is a mighty and formidable weapon, but will only allow itself to be lifted and wielded by a member of the female race. No man, despite his strength (or magic), can even lift the Warhammer from the ground, highly frustrating all of those (male) berserkers. The weapon is currently in possession of the Troll Queen. The PCs are hired by their
Queen to to retrive this legendary weapon.
I can keep going, but I'll stop now